Which on the four couples chaiming tha baby with O+ blood type are possible the biological parents of it ?

Options

A. AB- and A+
B. A+ and O-
C. O+ and AB+
D. B- and O-

Answer

To determine which of the four couples could be the biological parents of a baby with O+ blood type, we need to analyze the possible blood types of the parents and how they can combine to produce an O blood type child.

### Step-by-Step Solution:

1. **Understand Blood Type Genetics**:
- Blood types are determined by alleles. The alleles for blood types are:
- A: IA (dominant)
- B: IB (dominant)
- AB: IAIB (co-dominant)
- O: IOIO (recessive)
- The positive (+) or negative (-) refers to the Rh factor, which is separate from the ABO blood group system.

2. **Identify the Blood Types of the Couples**:
- Let's denote the couples and their blood types:
- Couple 1: A (IA) and B (IB)
- Couple 2: A (IA) and O (IO)
- Couple 3: O (IO) and AB (IAIB)
- Couple 4: B (IB) and O (IO)

3. **Analyze Each Couple**:
- **Couple 1 (A and B)**:
- Possible combinations: IAIB (AB), IAIO (A), IBIO (B).
- No O blood type possible.
- **Couple 2 (A and O)**:
- Possible combinations: IAIO (A), IOIO (O).
- O blood type is possible.
- **Couple 3 (O and AB)**:
- Possible combinations: IOIA (A), IOIB (B).
- No O blood type possible.
- **Couple 4 (B and O)**:
- Possible combinations: IBIO (B), IOIO (O).
- O blood type is possible.

4. **Conclusion**:
- Couples 2 (A and O) and 4 (B and O) can have a child with O blood type. However, since the baby is O+, we need to consider the Rh factor.
- If either parent is Rh positive, the child can be Rh positive. Since both couples have at least one parent who can be Rh positive, they are both possible biological parents.

### Final Answer:
The possible biological parents of a baby with O+ blood type are:
- Couple 2: A (IA) and O (IO)
- Couple 4: B (IB) and O (IO)